Made a router planing jig, but now some questions

As the title says, I made a router planing jig. I used 3/4” ply for the base, with 2×4s for the rails (I think I need to use something more narrow).

Couple of questions:

1. due to the width of my rails, I’m having to “prop” my slab up a bit just for the router to reach it. That’s a problem I should fix by using narrower rails right?

2. let’s say you lay a cutting board on this thing. Shouldn’t I shim it until it’s level (using a level)? I think I’m missing something here. I made the damned thing but I can’t found tips on how to actually use it.

3. As I go along, will I always have small ridges from each pass? Maybe it’s my setup, I don’t know.

Thanks guys, I’m learning a lot, and teaching myself as I don’t have anyone else I can go to.

4 replies so far

1. due to the width of my rails, I m having to “prop” my slab up a bit just for the router to reach it. That s a problem I should fix by using narrower rails right?

Not sure what you’re describing here. There should only be the 3/4” thickness of the plywood base bewteen the router base and your stock.

2. let s say you lay a cutting board on this thing. Shouldn t I shim it until it s level (using a level)? I think I m missing something here. I made the damned thing but I can t found tips on how to actually use it.

You shouldn’t need to if you made the cutting board reasonably accurately.

3. As I go along, will I always have small ridges from each pass? Maybe it s my setup, I don t know.

What kind of bit are you using? Even with a planer bit, there will be some slight discrepancy from pass to pass. I believe this is mostly from the sled flexing.

Here is a pic of the rig I used to flatten a workbench top maybe it will help:

Yes size your rails appropriately for your use. Sounds like you need to make your rail height shorter or cut plywood spacer to fit inside rails to raise work closer to router bit.

I just put two small dabs of hot glue on the board and press to base (I used melamine panel). That face becomes your reference face once you route it flat. As mentioned above as long as you are relatively flat to begin with not issues as just takes a little overall thickness from the board depending on how uneven it is. Once I get one side flat then flip it and use some wedges between the board and rails and secure the board and the route the other side.

I have been using a 3/4 straight router bit and have had no issues with ridges but would likely switch to a larger bowl/dish cutter router bit if decided to make more cutting boards. If sled is flexing going to be an issue with ridges unless you reduce the flex. My sled is 3/4 ply with oak side rails. Haven’t had any issues with flex but my set up isn’t very wide.

I made a planing jig for some walnut boards that were too wide for my jointer. It worked quite well.

1. The sides of my jig were also too high for the stock. I laid a piece of MDF under the board to raise it up enough.

2. First step – Make sure your jig is positioned flat (no twist). For mine, which was made 8’ long and only 12” wide, I simply laid a level across the jig over the horses it was laying on and shimmed until the bubble matched on both ends. The boards I planed were not flat and needed some shimming. I slipped a narrow shim under the high corners until they just contacted the board and provided full support. You don’t want to lift the board with the shim. I then placed wedges on the sides of the board to prevent any movement while routing. Hot glue would work better as I found the wedges wanted to spread the sides a little and caused the router sled to get a little tight but it did not cause any major issues.

3. I used a dado bit that left slight ridges in the board. They were visible but I really couldn’t feel any discernible ridge or impression. After planing the other face, it only took about 1/128th pass on the routed face to remove the marks.

The latest Woodsmith magazine that showed up in the mail a couple of days ago happens to have an article in the December issue about using a router jig to flatten cutting boards after glue up. You can see their setup on the cover here: http://www.woodsmithlibrary.com/view/issue/228/You may be able to get a free trial issue.

In their setup, the rails are simply 1-bys ripped to width needed so that the router carriage is the appropriate height above the board you are flattening. They simply clamped the rails to the sides of the board with a spacer that is lower than the board being flattened so that the bit does hit the rails. They actually used a bench vise and dogs but bar or pipe clamps would work too. If you at getting ridges, you may be getting too much flex from your carriage. Also, a bowl bit with rounded edges will reduce tearout which may also be causing ridges.

BTW, Woodsmith magazine is a great magazine for anyone learning woodworking. It has great tips and techniques and the plans are very well documented and easy to follow. If your budget allows I highly recommend buying their backissue DVD. It can be easily searched for articles, techniques, tips and project plans and you can print articles and plans to take into the shop. You can actually browse the index and try the search feature at their website to see how it works ad just how much information is available on the DVD: http://www.woodsmithlibrary.com/browse/

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.